<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			
			.box1,.box2{
				width: 150px;
				height: 150px;
			}
			/*
			 #main{
				color: red;
				font-size: 32px;
			}
			
			#main  .box1{
				background: red;
			}
			*/
			.main{
				color: red;
				font-size: 32px;
			}
			
			.main  .box1{
				background: red;
			}
			
			#box1_id{
				background: lightblue;
			}
			
			
		</style>
	</head>
	<body>
		<div class="main">
			id=main 的div
			<div class="box">
				<div id="box1_id" class="box1">
					box1
				</div>
			</div>
			<a href="#">test</a>
			<div class="box2">
				box2
			</div>
		</div>
		
	</body>
</html>
